Lead-free soldering guideline (NoNE)

Published 25/02/2011

Last updated 20/05/2011

Lead was one of the earliest heavy metals to be identified as a toxic environmental pollutant in widespread use throughout the world. Its use has been or is being phased out in many applications -- paints and leaded petrol, for example -- but the electrical and electronics (EE) sector has proved a stubborn case, in part because lead is still a key component of tin-lead solders used in equipment and components, notably printed circuit boards (PCBs).

The drive to excludelead from EE products originated in Japan, where Sony found that advertising equipment as "lead-free" increased its market share. A new and powerful impulse was the introduction of EU directives for managing waste electrical and electronic equipment (WEEE) and restricting hazardous substances in product manufacture (RoHS).

A ban on the use of lead in electronics assembly in Europe was clearly inevitable. Naturally, the prospect generated worldwide interest in the development and implementation of lead-free solders. There are numerous lead-free solders available, some of which have been used in electronics production already. High-temperature solders have been used successfully in automotive applications, and some companies have blended these materials into their processes for consumer and military/aerospace applications. For most mainstream applications, tin/silver/copper (SnAgCu) appears to be the most popular replacement. This alloy has also been chosen to be the most popular benchmark, with SnPb (tin-lead) being the baseline, for testing any other lead-free alloys.

Given the higher melting points involved, there are implications for every stage of the lead-free PCB manufacturing, assembly and testing processes. There is also a new set of environmental issues, some of which are addressed by another Nordic Innovation Centre project, GreenPack (www.greenpack.org).

Many businesses anticipate difficulties in facing these challenges, and a number of them have joined forces through the NoNE project to coordinate their efforts to adjust to the ban.